Human vitamin K 2,3-epoxide reductase complex subunit 1-like 1 (VKORC1L1), expressed in HEK 293T cells and localized exclusively to membranes of the endoplasmic reticulum, was found to support both vitamin K 2,3-epoxide reductase (VKOR) and vitamin K reductase enzymatic activities. Michaelis-Menten kinetic parameters for dithiothreitol-driven VKOR activity were: K(m) (μM) = 4.15 (vitamin K(1) e...

Cystic fibrosis (CF) patients are at high risk for vitamin K deficiency. The effects of vitamin K supplementation are very ambiguous. Therefore, we aimed to define the determinants of vitamin K deficiency in a large cohort of supplemented - 146 (86.9%) and non-supplemented - 22 (13.1%) CF patients. Vitamin K status was assessed using prothrombin inducted by vitamin K absence (PIVKA-II) and unde...

The importance of vitamin K to coagulation is well known but there is increasing evidence that vitamin K has a diverse role in the body including the maintenance of bone health, preventing inappropriate calcification in soft tissues, and a protective role in inflammation. There is evidence that most, if not all, of these non-coagulation functions require higher dietary intakes than those requir...

OBJECTIVE To assess unexpected associations between childhood cancer and pethidine given in labour and the neonatal administration of vitamin K that had emerged in a study performed in the 1970 national birth cohort. DESIGN AND SETTING 195 children with cancer diagnosed in 1971-March 1991 and born in the two major Bristol maternity hospitals in 1965-87 were compared with 558 controls identifi...

Atkins GJ, Welldon KJ, Wijenayaka AR, Bonewald LF, Findlay DM. Vitamin K promotes mineralization, osteoblast-to-osteocyte transition, and an anticatabolic phenotype by -carboxylation-dependent and -independent mechanisms. Am J Physiol Cell Physiol 297: C1358–C1367, 2009. First published August 12, 2009; doi:10.1152/ajpcell.00216.2009.— The vitamin K family members phylloquinone (vitamin K1) and...

PURPOSE The role of vitamin K in the prevention and treatment of osteoporosis and arterial calcification is examined. SUMMARY Vitamin K is essential for the activation of vitamin K-dependent proteins, which are involved not only in blood coagulation but in bone metabolism and the inhibition of arterial calcification. In humans, vitamin K is primarily a cofactor in the enzymatic reaction that ...

The dose of vitamin D that some researchers recommend as optimally therapeutic exceeds that officially recognized as safe by a factor of two; it is therefore important to determine the precise mechanism by which excessive doses of vitamin D exert toxicity so that physicians and other health care practitioners may understand how to use optimally therapeutic doses of this vitamin without the risk...

BACKGROUND One of the causes of unstable anticoagulant control in patients using vitamin K antagonists is a fluctuating intake of vitamin K. Research suggests that patients with a low dietary intake of vitamin K have a less stable anticoagulant control than patients with a higher intake. OBJECTIVES To study whether supplementation with a low daily dose of vitamin K improves anticoagulant cont...